Add preferred default release profile settings (#55)

* Add preferred defaults to `[profile.release]` section

* Add preferred profile.release defaults for contract build

* Remove [release.profile] section, update to scale-info release

* Fmt

* Fix remaining type-metadata reference in template

* Remove unused default impl of Profile

* OptLevel refactoring

* Indent test toml for readability

* Specify exact Lto values

* Make OptLevel consistent with Lto (no option)

* Revert to using type-metadata until ink! 3.0 release